net: remove unused icmp_ioctl() definition.

The patch removes unused icmp_ioctl() method definition in
include/net/icmp.h.

Signed-off-by: Rami Rosen <ramirose@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/icmp.h

@@ -41,7 +41,6 @@ struct net;
 
 extern void	icmp_send(struct sk_buff *skb_in,  int type, int code, __be32 info);
 extern int	icmp_rcv(struct sk_buff *skb);
-extern int	icmp_ioctl(struct sock *sk, int cmd, unsigned long arg);
 extern int	icmp_init(void);
 extern void	icmp_out_count(struct net *net, unsigned char type);